1. Field of the Invention
This invention relates to a connector for connecting equipment to underwater cables, such as underwater cables used in seismic testing. More particularly, it relates to a connector which makes it possible for equipment to be readily attached and detached from an underwater cable by hand without the need for any tools.
2. Description of the Related Art
In marine seismic exploration, a cable, commonly referred to as a streamer cable, is towed underwater by a surface vessel. An array of hydrophones is mounted in the cable, and an acoustic source or gun is fired to force an impulse of compressed air into the water, creating a bubble. The collapse of the bubble generates acoustic pulses that radiate through the water and into the earth. Reflections of the pulses off geologic structures are picked up by the hydrophones, and data representing the detected reflections are transmitted to the surface vessel. By analyzing the reflections, it is possible to discover subsea formations of oil or gas.
It is desirable to accurately control the depth of the cable as it is being towed through the water. For this purpose, depth control mechanisms, commonly referred to as "cable-leveling birds", are attached to the cable at intervals along its length. The depth control mechanisms are equipped with adjustable diving planes, the angles of attack of which can be varied by motors in the depth control mechanisms so as to maintain the cable at a desired depth.
Each depth control mechanism is detachably connected to the cable by one or more collar-shaped connectors, which are semi-permanently attached to the cable. Attaching and detaching a depth control mechanism from a connector frequently entails the manipulation of one or more bolts or screws and requires the use of various tools such as a hex wrench or a screw driver. This makes the process of attaching and detaching the depth control mechanism time-consuming and difficult, especially on the deck of a rolling ship, and the difficulty increases with the severity of sea conditions. Often a damaged outer section of the connector must be replaced. Attachment screws must be removed to separate the outer section of the connector. The removal of screws and their reinsertion in a replacement outer section require the use of tools and take time. Furthermore, after the screws are removed, they can easily become lost and washed overboard. Once the depth control mechanism is detached from the cable, the cable with the collar-shaped connectors attached to it is typically wound up on a large reel. As layers of the cable accumulate on the reel, the connectors on the inner layers may be crushed against the cable, damaging the skin of the cable and/or the connector itself. Thus, conventional connectors for underwater cables have a number of problems with respect to ease of use.